JPH0646038B2 - Axial ring fan - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial flow ring fan, and more particularly, to an axial flow ring fan capable of increasing fan operating efficiency and reducing fan noise.

An example of a known axial flow fan is U.S. Pat. No. 4,35.
No. 8,245 and No. 4,569,632. The former patent specification shows a fan whose blades are curved forward. In conventional form, these fans are made from injection molded plastic so that the hub, vanes and rings are a unitary structure.

The fan of the present invention has forwardly curved (skewed) blades, each leading edge of which has a somewhat sinusoidal shape when viewed in a circumferential direction. This shape is defined by the change in pitch ratio for the vanes along the radial region of the vanes. More specifically, it is defined as a function of the dimensionless radius of the blade as the ratio of the pitch ratio to the average pitch ratio. The characteristics in that case are almost constant between the dimensionless radii of 0.4 and 0.495, decrease between the dimensionless radii of 0.495 and 0.55, and the dimensionless radii of 0. It is almost constant between 55 and 0.675, increases when the dimensionless radius is between 0.675 and 0.85, and decreases when the dimensionless radius is greater than 0.85. The pitch ratio at a particular dimensionless radius is 6.28 times the dimensionless radius, which is the tangent times the angle Q, which is the vane along the particular dimensionless radius. First extending between the leading edge and the trailing edge of the blade as viewed in projection of a cross section of the blade onto a plane connecting the leading edge and the trailing edge of the blade.
Is an acute angle formed by a second line extending through the trailing edge point and being perpendicular to the direction of the projection. The blade average pitch ratio is the average value of the pitch ratio in the numerical value of the dimensionless radius of the blade, which is at least sufficiently close to the actual average value. In the case of the fan disclosed herein, the pitch ratio with respect to the average pitch ratio is about 1.07 when the dimensionless radius is between 0.4 and 0.495 and is about 1.07 when the dimensionless radius is between 0.55 and 0.675. Approximately 1.044 and approximately 1.4 when the dimensionless radius is 0.85.
105.

In the fan manufactured based on the principle of the present invention, the improvement of the axial flow, the improvement of the internal operation efficiency, and the reduction of the fan noise are achieved, and the noise has a remarkably reduced rotational noise component. The sound quality of the fans has been improved.
The features of the present invention will now be described with reference to the accompanying drawings which illustrate advantageous embodiments made in accordance with the best mode presently contemplated for carrying out the invention.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an axial front view of a fan embodying the principles of the present invention.

2 is a side view of the fan of FIG.

FIG. 3 is an enlarged cross-sectional view taken along line 3-3 of FIG.

FIG. 4 is an enlarged cross-sectional view as seen in the direction of arrow 4-4 in FIG. 1, showing the shape of the cross-section projected for the purpose of defining the blade pitch.

5-14 are enlarged projection cross-sectional views taken along respective transverse lines 5-14 of FIG.

FIG. 15 is a partially enlarged view of each front edge portion.

FIG. 16 is a partially enlarged view of the trailing edge portion of each.

FIG. 17 is a graph illustrating a certain relationship included in the fan blades.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1 and 2 show the general construction and arrangement of an axial ring fan 20 embodying the principles of the present invention.
The fan 20 includes a central hub portion 22, an outer ring 24,
And a number of vanes 26 extending radially between the hub portion 22 and the outer ring 24. The blades 26 are curved forward in the rotation direction of the fan. The leading edge of the blade is shown at 28 and the trailing edge is shown at 30. The cross-section of FIG. 3 represents the typical shape of the leading edge of each vane. Figure 3
As can be seen in the figure, this shape is somewhat sinusoidal in shape, which is the axially depressed region 3
2, which is located radially inward of the axially lifted region 34, the depressed region 32 as seen in the axial direction of FIG. 36
, And the unidirectionally swept region 34 occupies a zone approximately equal to dashed line 38. The dashed lines 36 and 38 do not then represent a distinct transition, but rather the zones should be considered to smoothly intermix with each other and transition to the rest of the vane.

The cross sections shown in FIGS. 4 to 14 are projected cross sections at different radii. FIG. 4 illustrates how the cross-section of FIG. 4 designated by reference number 40 is projected onto cross-section 42. The radii from the center of the fan are drawn at different points along the cross-section 40 and then projected perpendicularly to a line 44 extending through the trailing edge point of the cross-section. A line 46 drawn between the leading and trailing edges of cross section 42 intersects line 44 and defines angle Q. The pitch ratio of a particular cross section through the vane is 6.28 times the dimensionless radius of the tangent Q times cross section, as represented by cross section 4 through transverse line 14. Each blade has the characteristics defined by the graph of FIG. FIG. 17 shows the pitch ratio with respect to the average pitch ratio as a function of the dimensionless radius of the blade. The pitch ratio to the average pitch ratio when the dimensionless radius is between 0.4 and 0.495 is approximately 1.07. The pitch ratio to the average pitch ratio when the dimensionless radius is between 0.55 and 0.675 is approximately 1.044. The pitch ratio to the average pitch ratio when the dimensionless radius is 0.85 is about 1.105. The pitch ratio to the average pitch ratio decreases when the dimensionless radius lies between 0.495 and 0.55 and increases when the dimensionless radius lies between 0.675 and 0.85, And when the dimensionless radius is larger than 0.85, it is reduced.
When actually manufacturing a fan based on the principles of the present invention, a tolerance of plus or minus 0.03 with respect to the dimensionless radius is allowed. The average pitch ratio is the average value of the pitch ratios over many dimensionless radii of the vanes, which value is at least almost fully equal to the actual average pitch ratio.

Claims (2)

[Claims] 1. An axial flow fan having a plurality of blades which extend between a central hub portion and an outer ring and are curved forward, each blade having the following characteristics. , That is, the pitch ratio to the average pitch ratio is a function of the dimensionless radius of the blade, and the dimensionless radius is 0.4 ± 0.03 and 0.
495 ± 0.03, it is almost constant, the dimensionless radius decreases between 0.495 ± 0.03 and 0.55 ± 0.03, and the dimensionless radius is 0.55 ± 0. 03 and 0.6
It is almost constant between 75 ± 0.03, the dimensionless radius increases between 0.675 ± 0.03 and 0.850 ± 0.03, and the dimensionless radius is 0.850 ± 0. When it is larger than 0.03, it decreases, and the pitch ratio at a certain dimensionless radius is 6.28 times the dimensionless radius of the tangent Q times, in which case Q is a certain dimensionless radius. Through a trailing edge point and a first line extending between the leading and trailing edges of the blade as seen in projection of the blade's cross-section onto a plane connecting the leading and trailing edges of the blade Is an acute angle formed by a second line extending perpendicularly to the direction of the projection portion, and the average pitch ratio of the blades is an average value of the pitch ratios at a number of dimensionless radii of the blades, An axial-flow ring fan, characterized in that it is at least nearly equal to the actual average value. 2. The pitch ratio with respect to the average pitch ratio is approximately 1.07 between the dimensionless radii of 0.4 ± 0.03 and 0.495 ± 0.03, and the dimensionless radius of 0. 55 ±
Approximately 1.0 between 0.03 and 0.675 ± 0.03
44. The axial flow ring fan according to claim 1, wherein the axial flow ring fan has a dimension of 44 and is approximately 1.105 when the dimensionless radius is 0.850.